The invention relates to a method for the non-invasive determination of the position and orientation of prominent structures inside the body of a human being or an animal, wherein the body is irradiated with ultrasonic radiation in the area of the prominent structure by means of an ultrasonic head which emits ultrasound and receives ultrasound, the ultrasonic radiation reflected on the prominent structure is received, and an image corresponding to the travel time of the reflected radiation is represented on a display.
The invention further relates to an apparatus for performing this method.
To determine certain prominent structures inside a body, for example, certain bone structures, and to locate their exact position and orientation relative to the body, it has so far been necessary to open the body and to detect these structures inside the body with a probe whose position and orientation relative to the body can be determined by means of, for example, a navigation system.
Information on the position and, if required, orientation of the prominent structures relative to the body is thereby obtained.
A drawback of this method is that an opening in the body is required therefor. When such structures are palpated through soft tissue, inaccuracies may occur.
On the other hand, it is known to scan body structures inside the body via ultrasonic radiation. In known ultrasonic scanning methods, ultrasonic radiation is directed into the body via an ultrasonic head, is reflected there at prominent structures, and the reflected radiation is picked up again by the ultrasonic head. The distance of the reflection surfaces from the ultrasonic head can be determined from the travel time, and also the position of the prominent structures from the radiating direction of the ultrasonic head. All in all, the shape of the prominent structures can thereby be detected and imaged, but exact details of position and orientation relative to the body are not obtained.
The object of the invention is to so develop a method of the generic kind that the precise position and orientation of prominent structures in the body can be determined relative to the body without intervening in the body.